In recent years, the public has become increasingly aware of the environmental problems associated with the unregulated use of petroleum products. This has prompted the government to regulate not only the burning of petroleum fuels, but also the processing and the transfer of raw petroleum products. In particular, the government has focused on controlling the emission of hydrocarbon vapors and other pollutants which are released when volatile petroleum products come into contact with the atmosphere.
Although the regulation of petroleum vapor emissions was limited at first to stationary sources, such as refineries and tank farms, the scope of government regulations has gradually expanded to include mobile sources such as cars, ships, airplanes and trucks. In general, stationary sources of vapor emissions have been required to provide means for processing hydrocarbon emissions, while mobile carriers of volatile petroleum products have been required only to collect and to present petroleum vapors for further processing. For example, gas stations in California are required to provide special hoses which gather the vapors otherwise vented to the atmosphere during the fueling of an automobile. The mobile source of hydrocarbon vapor emissions, in this case the automobile, is required only to present petroleum vapors for further handling by the gas station.
Several jurisdictions have also adopted pollution control laws which place limits on petroleum vapor emissions during the loading of marine cargo vessels with volatile petroleum products. Like the California laws governing gas stations, these laws generally require that stationary, shore-based facilities process the petroleum vapors. Ships carrying petroleum products must therefore possess a means for presenting such vapors to a shore-side facility unless they have some other means of controlling petroleum vapor emissions.
In addition, some shore-side vapor processing facilities require that vapors be inerted, or made non-explosive, before being presented to the facility. Vapors are normally inerted by channeling inert gases, such as CO.sub.2, into the compartments containing petroleum products. Ships presenting vapors to such facilities must therefore also be outfitted with inerting systems.
Although the component of petroleum vapor emissions most often targeted for regulation is hydrocarbon vapor, pollutants besides hydrocarbons are also released by volatile petroleum products. Some grades of raw petroleum, for example, contain hydrogen sulfide and other hydrogen-containing organic compounds. When released into the air, these compounds produce an unpleasant odor, which has led to the regulation of the release of such compounds in residential areas.
The current practice of ships calling on ports with pollution control requirements is to install piping on such ships which connects the venting systems of the storage compartments of such vessels to a common collection manifold, known as a header pipe. The vapors can then be ducted from this manifold to a shore-side facility for processing. However, if the ship does not already have an inerting system and the shore-side facility requires that inerted vapors be presented for processing, an inerting system must also be installed. The most common type of inerting system involves ducting the exhaust from a ship's engines to petroleum storage compartments. Barges, however, cannot be outfitted with conventional inerting systems because they do not possess the capability of generating large volumes of inert gas.
Since many jurisdictions, especially jurisdictions outside the U.S., do not yet have air pollution control requirements, many marine vessels are not equipped to control hydrocarbon vapor emissions. There is therefore a great need for a portable, cost-effective means of controlling petroleum vapor emissions which may be transported to a ship in need of petroleum vapor control.